Caption: Cystic fibrosis. Coloured chest X-ray of the lungs of a patient with cystic fibrosis. Bones, such as the ribs around the lungs, are green. Within the lungs the bronchial walls (orange) beside the spine (down centre) have thickened due to repeated infection. The diaphragm (blue, lower centre) is low because of airway obstruction. In cystic fibrosis, excess mucus production in the lungs leads to chronic infection. There is also an inability to absorb fats from food. The disorder is inherited from a mutated gene on chromosome 7. Despite treatment with antibiotics, physiotherapy and enzymes to aid food digestion, the disease often results in a much reduced life expectancy.